Hitherto, a tire test (tire uniformity test) has been performed on a product tire manufactured in a tire manufacturing line. The tire uniformity test measures tire uniformity (evenness) etc. of the tire and determines whether the tire is good or not.
A tire uniformity machine (tire testing device) for performing the tire uniformity test has a configuration in which a predetermined load is applied to a rim-fitted tire to press the tire onto a rotary drum, and a distance between a spindle shaft and a drum shaft is fixed, and then, the tire is rotated so that a force variation generated in the tire can be measured (for example, see Patent Literature 1). The tire uniformity machine measures a load variation (RFV: Radial Force Variation) in a direction in which the load is applied to the tire, a static load deviation (CON: Conicity) in a width direction of the tire, a load variation (LFV: Lateral Force Variation) in the width direction of the tire, etc.
A rim provided in the tire testing device, that is, a rim for tire testing for fixing a tire to be tested has a structure in which the rim can be divided vertically into two, that is, an upper rim and a lower rim, by which the tire can be mounted surely in a short time. For example, when the tire is conveyed into the testing device by a conveyor, of the upper and lower rims which have been held vertically separately from each other, the upper rim moves down from above and the lower rim moves up from below at the same time as the tire is conveyed into the testing device. Then, the upper and lower rims move to put the tire therebetween from above and from below respectively. Thus, the tire can be attached to the rim for tire testing.
The rim for tire testing is made of steel or SUS and designed to be thick. The rim for tire testing has a structure in which the rim for tire testing has rigidity high enough to withstand the internal pressure of the tire. In addition, the rim for tire testing is formed so as to satisfy roundness high enough to reduce deflection during rotation. Thus, the tire uniformity can be measured with high accuracy. Further, when the rim for tire testing is made of steel, plating for preventing rust or abrasion may be performed on a surface of the rim for tire testing.
To the rim for tire testing formed thus, the tire to be tested is fixed in contact with the rim for tire testing at two points, that is, a vertically central portion (a rim base portion in the present invention) of a rim body and an upper end portion (a rim flange portion in the present invention) of the rim body. More specifically, the rim base portion is contact with an inner peripheral surface of a tire bead portion so as to position (center) the horizontal position of the tire at the center of the testing device. In addition, in order to support the radial load of the tire, the rim base portion is attached to the tire in an interference fitting manner with no space between the rim base portion and the tire bead portion. Further, the outer diameter of the rim base portion is designed to be larger than the inner diameter of the tire, so that the tire can be pressed into the rim base portion by use of a load generated in the tire when the tire is filled with compressed air.